Limitations of BMI in Pregnancy

• Using BMI, in pregnancy in not accurate.

• It should be done pre and post pregnancy.

• BMI does not really convey differences in shape that are relevant to obstetric anaesthetists and for the surgery during normal pregnancy and instrumental delivery or C/S.

The Scale of the Problem

• WHO: “Obesity is a worldwide epidemic”.• 250 Million obese people, 7% of world

population. • USA: 65% of adults are obese or

overweight. NHANES.• UK: Fastest growing obese population.• 16% of obstetric patients >100kg.• 19.6% of women in the reproductive age

are above BMI >30.

• Transition from Overweight to Obesity Worsens Pregnancy Outcome in a BMI-dependent Manner. – Raatikainen K, Heiskanen N, Heinonen S. Obes

Res. 2006 Jan;14(1): 165-71.

– The risk of perinatal death more than doubles in the transition from an overweight to an obese condition.

• Teratology public affairs committee position paper: Maternal obesity and pregnancy. – Scialli AR. Birth Defects Res A Clin Mol Teratol.

2006 Feb; 76(2): 73-7.

• The literature suggests that women with a body mass index (BMI) >/=30 have approximately double the risk of having a child with a neural tube defect (NTD) compared to normal-weight women, and the increased risk associated with higher maternal body weight does not appear to be modified by folic acid supplementation.

• The prevalence and impact of overweight and obesity in an Australian obstetric population. – Callaway LK, Prins JB, Chang AM, McIntyre

HD. E Floor, Clinical Sciences Building, Royal Brisbane and Women’s Hospital, Herston QLD 4029, Australia. lcallaway@somc.uq.edu.au. Med J Aust. 2006 Jan 16; 184(2): 56-9.

• 11 of 252 women - BP, GDM, hospital admission, C/S, birth defect, preterm delivery, NICU admission.

• BMI should be routinely recorded on perinatal data collection sheets.

Recommendations for Weight Gain During Pregnancy

Description Recommended Total Weight Gain (lbs)

Underweight 28 – 40 (12-17 kgs.)

Normal weight 25 – 35 (11-15 kgs.)

Overweight 15-25 (6.5-11 kgs.)

Obese 15 (6.5 kgs.)

• Note multiple pregnancies.

Recommendations for ALL women (including preconception):

• Inform and counsel women about the health risks associated with overweight and obesity.

• Encourage a healthy diet– Diets that restrict particular food groups are

discouraged, especially during pregnancy.

• Screen for hypertension and diabetes mellitus in women who are at risk.

• Counsel women to consume adequate folic acid, iron and calcium.

cont. Recommendations…

• Encourage regular exercise (30 minutes of moderate physical activity daily)

• Counsel women to quit smoking

• Counsel women to avoid consuming alcohol during pregnancy.

• Discuss recommended weight gain during pregnancy.

After Pregnancy (postpartum)

Recommendations for “for ALL women” PLUS the following:

• Encourage breastfeeding.

• Counsel women to return to a healthy weight

• For women who are attempting to or have quit smoking, continue support to prevent postpartum relapse.

Odds Ratios of Obesity and Overweight vs. Normal Weight Status on Selected Pregnancy Outcomes: Missouri Singleton Pregnancies

1999-2003

Outcome

Obesity vs. Normal Odds Ratio

95 percentconfidence interval

Very low birth weight (<1500 grams) 1.23 1.15 1.32Macrosomia (>4499 grams) 2.52 2.36 2.69Early preterm (<32 weeks) 1.09 1.03 1.16Congenital anomalies 1.17 1.09 1.25Fetal death 1.30 1.17 1.45Neonatal (<28 days) death 1.31 1.15 1.51Post-neonatal (1-11 months) death 1.17 0.97 1.42Perinatal (fetal or neonatal death) 1.31 1.20 1.43Infant (<1 year) death 1.26 1.13 1.42Fetal or infant death 1.29 1.19 1.39

Note: Odds ratios calculated using multivariate logistic regression with the following covariates: race, education, age, marital status, & smoking status of mother and birth order.

• Infertility – PCO

– Early pregnancy loss _________

– Insulin resistant

• Birth defects particularly neural tube defect

• Labor delivery complications– Preterm labour

– Prolonge 2nd stage

– Large babies shoulder dystocia + instrumental delivery

– C/S C.P.D.

– Need for Oxytocin

• Antenatal complications

Maternal D.M. PET Hypertension

Maternal complications

• Preterm Labour – could be iotrogenic due to D.M., PET, HTN.

• Low birth weight

- Women with relatively low pre-pregnancy weight more like to have PTL + L.B.W.

cont. Maternal complications

• Postpartum haemorrhage

• Wound infection

• Post C/S endometritis prolonged hospitalization

• Postpartum thromboembolic manifestation DVT, P.E.

Fetal complications

• Neonatal death

• Birth defect – neural tube defect

• Low Apgar Score

• More NICU admission

• Cedergren MI (2004): A Swedish, population-based cohort study (n=805,275)

Study Group Control Group – Normal Weight

BMI > 40

PET X 5 fold

Still Birth x 3 fold

LGA x 4 folds

Early NND x 3.5 fold

• Baeten JM et al (2001): A population-based cohort study in Washington state based on birth data (n=96,801).

– GDM

– PET

– Eclampsia

– C/S

– LGA infants